Non-woven products



Nov. 13, 1962 H. w. coATEs ErAL 3,063,454

NON-WOVEN PRODUCTS Filed Feb. 26, 1959 The present invention relates to reinforcement of nonwoven fibrous structures such as sanitary napkins and to other non-woven brous structures.

Non-Woven webs are especially suited for applications where softness and porosity are called for, such materials being relatively inexpensive to manufacture. Because of the absence of interlocking as in knitting or Weaving, however, non-woven unbonded webs are characterized by extremely low strengths.

Itis an object of the present invention to provide a reinforced non-woven structure of considerably increased strength.

lt is a further object to provide a reinforced, strong non-woven structure having the reinforcement firmly embedded in the structure.

Another object of the invention is to provide procedures for producing novel reinforced, strong non-woven structures.

Still yanother object is to provide non-woven coverings for disposable items such as sanitary napkins or the like.

Other objects and adavantages of the invention will become apparent from the following detailed description and claims.

In accordance with one aspect of the invention, a iibrons structure is formed of potentially adhesive fibers and of other fibers containing an activating agent such as a solvent, plasticizer or swelling agent for the potentially adhesive fibers. The activating agent, advantageously upon application 'of pressure land/or heat, attacks the potentially adhesive bers and causes them to be bonded to the other fibers. Such bonding of the other fibers into the matrix is ensured by virtue of the fact that the only source for activating agent for the potentially adhesive fibers in the other bers.

In accordance with another aspect of the invention the potentially adhesive fibers are included in a nonwoven web and the other bers are included in yarns arranged to serve as a reinforcement for the web. lf suiiicient heat and/ or pressure are employed, and if the yarns contain sufficient activating agent, the activating agent may be caused to migrate sufficiently from the yarns to effect bonding of the fibers in the web to one another in addition to bonding of the potentially Iadhesive fibers in the web to the reinforcing yarns. If desired, prior to application of heat and pressure a second non-woven web may be superposed on the reinforcing yarns containing activating agent to form a non-woven product having an embedded reinforcement. Any number of layers of nonwoven webs and yarn reinforcements may be alternated.

The patterns in which the reinforcement yarns are laid down will determine the ultimate strength of the article. Approximately equal strengths in longitudinal and transverse directions of the non-woven can be attained by employing parallel yarns of the same composition spaced equally warp-wise and fill-wise. lf the yarns are not of the same composition and/ or the spacing between parallel yarns is varied, differential strengths warp-wise and lill-wise can be attained, as desired. yOne particularly useful grid arrangement of yarns includes a plurality of parallel yarns laid down in one direction and superposed oy a plurality of additional yarns extending at 90 angles to the iirst-named yarns substantially in the same plane. The yarns need not be woven or otherwise interlocked, since the potentially adhesive bers when activated will 3,0@354 Patented Nov. 13, 1962 bind the crossing yarns to one another as well `as to the potentially adhesive fibers.

The non-woven web may be composed in whole or in part of potentially adhesive fibers representative examples of which include polyamides such as nylon, polyesters such as polyethylene terephthalate, acrylonitrile polymers and copolymers, olefin and olenic ester polymers and copolymers such as polyethylene, polypropylene, polyvinyl chloride, poly-vinyl acetate, and the like. Especially goed results are achieved with organic acid esters of cellulose such as cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate' formate, cellulose lacetate propionate, cellulose acetate butyrate, and the like. Of these, cellulose acetate is preferred.

Advantageously the potentially adhesive bers comprise more than about half of the non-woven web by weight. The component fibers may be crimped or straight and may range in denier from about 2.0 or less up to about 8.0 or even more. The no-n-woven web can be formed in conventional manner Ias by air blowing, cardiug, or the like, and may be parti-ally bonded in conventional manner. lts weight and thickness will vary with the intended end use. For most purposes the weight will range from about 0.10 to 1.0 and preferably about 0.2 to 0.5 ounce per square yard.

The reinforcing yarns may comprise monofilaments, a plurality of continuous filaments, plied yarns, spun staple yarns, or the like. The yarns may comprise any of the fibrous materials hereinabove recited and they may additionally comprise cotton or rayon, preferably high tenacity rayon having a tenacity in excess of about 5.0 grams per denier such as is obtained by saponiiication of cellulose acetate. excess of 3.0 grams per denier can be used in such small `amounts that they will not alter the feel of the non-woven product although they 4will impart appreciable reinforcement.

In any given specimen the yarns preferablycomprise inert fibers of chemical composition different from that of the potentially adhesive fibers so that the activating agent with which the yarn is wet will selectively attack the potentially ladhesive fibers. However, it is possible to utilize component yarns of the same chemical composition as the potentially adhesive fiber to obtain specific end use properties. Alternatively, the individual yarns can comprise a blend of inert bers and of potentially adhesive oers, or the reinforcement can comprise yarns of inert fibers alternated with yarns of potentially ad-- hesive bers.

The activating agent for the potentially adhesive ber can comprise a volatile solvent therefor but preferably it comprises a plasticizer which may or may not be volatile. Thus, when the potentially adhesive fibers are cellulose acetate, if the reinforcing yarns are cellulose, i.e. cotton'or preferably high tenacity rayon, the bonding may be effected with solvents such as acetone or methylene chloride Ibut is better effected with high boiling organic esters of carboxylic acids such as alkyl or aryl esters of citric acid,'

adipic acid, maleic acidgphthalicV acid, or organic esters of inorganic acids. suchas tributyl phosphate, tricresyl phosphate or alkoxy alkyl esters of these inorganic polybasic acids or organic polybasic acids, high-.boilingethers such as butyl ether of ethylene glycol, methyl ether of ethylene glycol, etc., high-boiling esters of polyhydricalcohols such as triacetin, glycoldiacetate and diacetin. The activating agents may be diluted with water, alcohol or other poor swelling agent to decrease the activation of the potentially adhesive fibers. The activating agent is incorporated in the reinforcing yarns preferably by a coating technique, e.g. immersing, dipping, spraying, kiss rolls, or the like, followed by wiping to remove excess liquid to prevent dripping. The amount of activating Yarns having tenacities in 3. agent picked upgcan be varied widelyand may ,range from about 2 to 20 and preferably 5 to 10% lby weight of the yarns.

Materialszproducedin accordance with the invention can be used ascomponents for building up laminates, for impregnation with plastics in making shaped structures, and the like.` They'are especiallyY suited for use as covers for-sanitary napkins in which application their strength, softness and relatively low cost are especially benelicial. Whereas a non-Woven web in, native state, or even after partial bonding and reinforcement with a wide mesh woven backing, cannot retain a safety pin or other fastener, thenovel non-wovens can -be held in place by pinning with no difficulty.Y For this end use, the nonfwoven webV is preferably applied to both surfaces of the reinforcing yarns. The web ranges in. weight from about 0.10 to 0.60 and preferably 0.20 to 0.40* ounce per square yard; Thereinforcing yarns may range in denier from about 30Vto 150 and are preferably laid parallel to one anothen'spaced about ls to, 1A inchapart. Preferably a second set of yarns, similarly constituted, isy laid cross-wise directly over the rst yarns. The amount of plasticizer in the yarns may range from; about 2 to 2O and. preferably about 5 to V10% by weight.

The accompanying drawing illustrates a preferred procedure and a representative product. of the'invention in the form vvoffasanitary napkin, this procedure and product being described in further detail inA Examples I and II. hereinbelow.

In. thev drawing,

FIGURE 1 is an. exploded diagrammatic view of an assembled' product of the invention before bonding;

FIGUREZ is a view of the .product assembled in FIG- URE 1 after bonding; and

FIGURE 3 is a schematic elevational view of the component layers of a sanitary napkin prior to folding.

In FIG. l, the exploded view of the laminate shows thevsuperimposed relationship of outer Webs of unbonded cellulose acetate Webs 11, 12 to the longitudinal and transverse regenerated cellulose yarns 13 and 14, respectively.

In FIG. 2,' ther component Webs 11 and 12 are not independentlyY identifiable. Yarns 13,' 14 are bonded at their crossing Vpoints as well as being bonded to the t bers of the web to form- Va single strong structure 15.

Numerous bersfwithin the product 15 are bonded to one another even Without directly contacting yarns 13 or 14, due to migration of the plasticizer initially contained infyarns 13, 14.

InFIGf.v 3 there isshown the stacked padv layers plus cover layer'for forminga sanitary napkin. The layers comprise the conventional three sheets of tissue paper 16, webfofviscoseber -17,"twosheets of Vtissue paper 13,

layer of Wood pulp-fiber 19, sheet of water repellent tissue-1 square yardjand composed of -3 denier cellulose'acetate bersaboutl inches long, was. placed von-a Hat table top.

High tenacity rayonyarns, made by saponifying steamed. Yand stretched` celluloseacetate multiilament yarn, com-A prising4laments. eachof .0.75 denier and twisted togetherwithj turn per inch-to-givea yarn of 210` grams tenacity Was cut into predetermined lengths which wereydipped in 'a rsolution,ofv15% by Weight of diacetin (glycerol diacetate) in Water;A The Wet lengths of yarn wereV squeezed to a lliquid pick-up of about by weight.

`Parallel yarns VWerelail longitudinally on the webV with' 1/s inchY spaces therebetween. Yarnswere alsoV laid transversely at ls inch intervals, resting on the longitudinal yarns. Another web identical with the first was placed on the stack, heavy paper was placed on top and a hot iron Was passed over the assembly several times to produce a composite structure as shown in FIG. 2. This can be used as the outer cover for sanitary napkins.

Example II The procedure of Example I can be repeated, substituting for the high tenacity rayon yarns 50 denier nylon yarns alternated with 50 denier cellulose acetate yarns, the Warp-wise yarns being spaced 8 to the inch and the transverse yarns being spaced 4 to the inch. The resulting non-woven product can be employed as the outer cover for a sanitary napkin constructed as shown in FIG. 3.

It is to be understood that the foregoing detailed description is given merely by Way of illustration and that many variations may be made therein without departing from the spirit of our invention.

Having described our invention what We desire to secure by Letters Patent is:

1. A strong, eXible, nonwoven, iibrous, laminate structure comprising at least lone non-Woven brous plasticizable web and a plurality of reinforcing yarns in substantially the same plane, on at least one surface of said web, said yarns carrying a pl-asticizer for the fibers of said web, said web fibers being plasticizcd to. render them adherent to said yarns lonly at the points of contact with said yarns and said yarns being bonded to said web only by said plasticized fibers.

2. A non-woven structure according to claim l, wherein some of said yarns extend in one direction and others of said yarns overlie said first-named yarns and extend in a second direction to afford reinforcement in a plurality of directions, migration of said plasticizer bonding said yarns to each other as well' as to said web.

3. A non-woven structure according to claim 1, wherein at least some of said yarns have a tenacity of at least about 3.0 grams per denier, the denier of the yarns varying from about 30 to about 150.

4. A non-Woven structure according to claim 1, wherein at least some of said yarns comprise fibers to which said activating agent is inert.

5. A non-woven structure laccording to claim l, wherein said yarns comprise rayon produced by saponication of cellulose acetate `and having a tenacity of at least about 5.0 grams per denier.

6. A non-woven structure according to claim l, wherein said yarns comprise nylon.

7. A non-woven structure according to claim 1, wherein said non-Woven web comprises cellulose :acetate fibers.

8. A non-woven ystructure according to claim l including a second non-woven fibrous plasticizable web disposed on the other surface of the plane `in which said yarns lie, said second web being bonded to lsaid rfirst web and to said yarns by the action of said plasticizer.

9. A non-Woven structure according to claim l, wherein said plasticizer is a liquid of low volatility.

10. Arsanitary napkin comprising in combination a covering as claimed in claim l and an adsorptive, nonwoven fibrous pad'contained Within said covering.

l'l. A sanitary napkin according to claim l0, wherein said covering includes a second non-woven ibrous plasticizable web disposed on the other surface of the plane in which said yarns lie, said lsecond web being bonded to said first web and to said yarns by the action lof said plasticizer.

l2. A sanitary napkin'according to claim l0, wherein said non-woven webs comprise cellulose acetate.

13j A sanitary napkin according to claim 10, wherein said yarnsV comprise rayon produced by saponiiication of cellulose acetate and having a tenacity of at least about 5.0 grams per denier. Y Y

14. A sanitary napkin according to claim 10, wherein said high-tenacity yarns comprise nylon.

15. A sanitary napkin according to claim 10, wherein said plasticizer is a liquid of low volatility.

16. The method of forming a strong fibrous structure which comprises forming a librous structure of potentially adhesive libere positioning a multiplicity of substantially uniplanar yarns containing an activating agent for said potentially adhesive bers adjacent said bers, and bonding said yarns to said potentially adhesive bers through the action of said activating agent.

17. The method according to claim 16, wherein said potentially adhesive bers are present in la non-woven web and said inert fibers yare present in a yarn serving as a reinforcement for said non-woven web.

18. The method according to claim 16 wherein said inert fibers comprise rayon produced by saponication of cellulose acetate and having a tenacity of at least about 5.0 grams per denier.

19. The method 4according to claim 16 wherein said potentially `adhesive bers comprise cellulose acetate.

20. The method according to claim 16, wherein said potentially adhesive ibers are plasticizable and said activating agent comprises a liquid plasticizer for said potentially adhesive bers, said liquid plasticizer being of low volatility.

21. A method of preparing a laminated, reinforced, non-woven, ibrous, soft sheet structure having high strength comprising pl-acing a non-woven web which includes potentially adhesive tibers on a support, superposing on said web in substantially the same plane a plurality of yarns containing an activating agent for said potentially adhesive bers, and applying heat and .pressure to said web and yarns whereby said activating agent causes said potentially adhesive ibers to adhere to one another and to said yarns.

2.2. A method of preparing a non-woven structure according to `claim 2l, wherein some of said yarns extend in one direction and others are placed to overlie said iirstnarned yarns :and extend in a second direction to afford reinforcement in a plurality of directions, application of heat and pressure bonding said yarns to one another at their cross-over points.

23. A method of preparing a non-woven structure according to claim 121 including the step of positioning a second non-woven yweb over said yarns prior to applying heat and pressure, said second non-woven web including potentially Aadhesive fibers also 'attacked by said activating agent, whereby said second web is bonded to said rstnamed web as well as to said yarns.

References Cited in the tile of this patent UNITED STATES PATENTS 2,294,898 Fourness et al Sept. 8, 1942 2,705,498 Johnson Apr. 5, 1955 2,833,283 Spahr et al May 6, 1958 2,900,980 Harwood 4 Aug. 25, 1959 

1. A STRONG, FLEXIBLE, NON-WOVEN, FIBROUS, LAMINATED STRUCTURE COMPRISING AT LEAST ONE NON-WOVEN FIBROUS PLASTICIZABLE WEB AND A PLURALITY OF REINFORCING YARNS IN SUBSTANTIALLY THE SAME PLANE, ON AT LEAST ONE SURFACE OF SAID WEB, SAID YARNS CARRYING A PLASTICIZER FOR THE FIBERS OF SAID WEB, SAID WEB FIBERS BEING PLASTICIZED TO RENDER THEM ADHERENT TO SAID YARNS ONLY AT THE POINTS OF CON-
 16. THE METHOD OF FORMING A STRONG FIBROUS STRUCTURE WHICH COMPRISES FORMING A FIBROUS STRUCTURE OF POTENTIALLY ADHESIVE FIBERS POSITIONING A MULTIPLICITY OF SUBSTANTIALLY UNIPLANAR YARNS CONTAINING AN ACTIVATING AGENT FOR SAID POTENTIALLY ADHESIVE FIBERS ADJACENT SAID FIBERS, AND BONDING SAID YARNS TO SAID POTENTIALLY ADHESIVE FIBERS THROUGH THE ACTION OF SAID ACTIVATING AGENT. 